High Pressure Aeroponics

Fire some mist across (or even directly at) some trampoline jump mat fabric (aka permatron) and see how much mist makes it through. Insulation works both ways, it can keep heat in as well as out. Water drains through the entire chamber floor which is much better than via a small drain at one end of the chamber. When roots reach the fabric floor (or walls) they are air pruned which stops them in their tracks and causes new laterals to form back along the length of the root, With a screen mounted above the floor of a plastic tote, the airspace below it will be very humid (not dry) so you wont get any air pruning. The roots will just pile up on the screen.
You should count yourself lucky you weren`t here

Click to expand...

I don't wanna hijack the thread but I saw you comment on the youtube vid with a atomizer fogger, you said it wouldn't work because of the size of the drops, but at 25 psi it puts out 30 to 100 micron droplets, wouldn't that work?

I guess thats the microfog / aerolife nozzle? I acquired one for testing several years ago and although the fog looks impressive its no good for aero. The ultrasonic resonator tube on the front of the nozzle is designed to generate very small droplet sizes even at low air pressures. If you buy one and find its no good, you can always use it as a paperweight

I guess thats the microfog / aerolife nozzle? I acquired one for testing several years ago and although the fog looks impressive its no good for aero. The ultrasonic resonator tube on the front of the nozzle is designed to generate very small droplet sizes even at low air pressures. If you buy one and find its no good, you can always use it as a paperweight View attachment 4089438

I`m still using chambers made from heavy duty woven polyprop fabric, only the top and end panels are solid.

Click to expand...

I have thought about this, and since I am still in the design stage of the root zone chamber (RZC), I might integrate root mats and the polypropylene (PP) walls. The PP walls would be half walls, as the 4'x8' tray walls have a 7" wall height already. The bottom of the tray would be covered with the root mats, to restrict root growth into the water runoff. I would still insulate the top from the light zone, and pump cool air to the area below, which contains the RZC. I think I can make the PP walls detachable for viewing or nozzle replacement, and that they will allow air flow to the chamber to remove any accumulated heat. What PP fabric do you use, and would you suggest any alterations to this design?

I use permatron, a very heavy duty black woven PP fabric commonly used for trampoline jumpmats. For detachable panels i`d use a velcro fixing method. To fabricate entire root chambers i weld the panels together using a handheld crimp sealer (see pic). A folded strip of baking parchment prevents the crimp plates from sticking. The 15mm wide seals are permanent and indestructable, located on the outside edges of the "box" so they can be used as fixing flanges. The fabric root chambers use passive evaporative cooling. As air passes over the outside surfaces of the fabric box, excess moisture in the fabric is evaporated and carried away. The sensible energy required for the phase change is taken from the inside of the chamber which cools it. Mist evaporating inside a well sealed root chamber, contrary to popular belief, doesnt provide much in the way of evaporative cooling, the chamber RH% is too high and there isnt enough air flow.

Research the "Boundry Layer hypothesis" in hydroponic science, it's a strong argument to not: (1.) have huge root mats, (2.) and/or running a system ignorant to this. Just because one may run HPA aero with 20ppm O2 does in no way mean that your roots are getting that. I find much how-to articles on google ignore that simple reality. So did I while I was experimenting with low flow rates and tiny tubes until I learnt the hard way.

More O2 inside the tight thick rootmat bundle will be magic--it's a strong reason why Aero and NFT work so well but only really for small plants that arent root bound in a tube or whatever. System built-in boundry layer elimination for optimal gaseous exchange ftw

If one timer can run 24/7 reliably so can two I use 12vdc pump, timers and solenoids for hpa. The timers pull 3mA when idle and 15mA when the SSR`s are active, next to nothing in running costs.
In most cases of DPDT switches and relays, pins 3 & 6 would be the commons. If thats the case you want +24v supply on pin 6, which switches to pin 5 or pin 8 (providing +24v to the individual timers). The outputs from the timers connect to pin 1 & pin 4 and pin 3 would be connected to the system solenoids. All the negatives commoned with a wire nut or connector block.
Running 2 timers 24/7 allows you to alter the night cycle timing when the lights are on, and the day cycle timing when the lights are off. Mine remember their settings but i cant change them unless they have power

Click to expand...

Spend couple of days trying to build the thing and had troubles to prevent current backflow from one timer to another. Even with using shottky diodes. It sort of worked but voltage at the end dropped to 17v. My electronic skills ain't that advanced to work out what's happening in the circuit, so I gave up and remembered your advise! I resoldered the whole thing so both timers is ON 24/7 and relay doing switching after timers. All working great! Big Thank You for the idea!

Attached Files:

Glad you`ve got it up and running. I have a few of those timers kicking around somewhere. If i remember correctly, the negative rail is switched. They are basic (not easy to hit the same setting twice) but ultra reliable and should run for years without any trouble.

Just because one may run HPA aero with 20ppm O2 does in no way mean that your roots are getting that.

Click to expand...

Hi HydroLynx,
Good stuff, I hear you about the difficulties getting O2 to massive root balls, it would be more difficult to permeate and supply optimal levels if the only available O2 was limited to what was dissolved in the water. There is another factor when thinking about O2 saturation and plants; the partial pressures of gasses. O2 is being consumed, and pressure reduced, so saturation doesn't occur. With a barely wet root and 21% atmospheric O2, the O2 is constantly diffusing back into the H2O. That fine layer of water allows the roots to function akin to our lungs in regards to diffusion and O2 supply.

I use permatron, a very heavy duty black woven PP fabric commonly used for trampoline jumpmats.

Click to expand...

Sweet! I searched, and searched for a supplier. I finally found one that sells trampoline fabric uncalendered, and it's a reasonable price, Funspot,com sells the fabric by the yard. I couldn't find permatron fabric here (I'm about fifty miles from Bete, so if you need their nozzles...) so I tried many different queries. Many came back with landscape fabric, until finally I came across the right material. They say that the uncalendered fabric has 15% more airflow. I have enough material to double it up, if the moisture evaporates too quickly. Thanks for the advice!

Hi HydroLynx,
Good stuff, I hear you about the difficulties getting O2 to massive root balls, it would be more difficult to permeate and supply optimal levels if the only available O2 was limited to what was dissolved in the water. There is another factor when thinking about O2 saturation and plants; the partial pressures of gasses. O2 is being consumed, and pressure reduced, so saturation doesn't occur. With a barely wet root and 21% atmospheric O2, the O2 is constantly diffusing back into the H2O. That fine layer of water allows the roots to function akin to our lungs in regards to diffusion and O2 supply.

Sweet! I searched, and searched for a supplier. I finally found one that sells trampoline fabric uncalendered, and it's a reasonable price, Funspot,com sells the fabric by the yard. I couldn't find permatron fabric here (I'm about fifty miles from Bete, so if you need their nozzles...) so I tried many different queries. Many came back with landscape fabric, until finally I came across the right material. They say that the uncalendered fabric has 15% more airflow. I have enough material to double it up, if the moisture evaporates too quickly. Thanks for the advice!

Awesome Kytaez! Keep us posted on your progress. I can't wait to see the system.

Yep! That was a first thing that puzzled me! As you said it's rock solid timers tho!

Cheers ZxcStaz ! Not really a system just yet waiting on solenoids and some fittings. I'll update with pictures as soon as I get going.
O2 in the sealed root chambers... Can we achieve minimum with additional hydrogen peroxide in the feed? Probably not.

H2O2 will break down to O2 and water, but it is also cytotoxic and a good reducing agent, so it can only be applied in low concentrations (way <3%). As it provides e- it will evolve O2, but it pretty much destroys everything in it's vicinity. Plants can tolerate it to an extent, but I wouldn't treat it as a vitamin. More O2 will be available through atmospheric diffusion, and therein lies the benefit of aero.

I have a plan to regulate the RZC temperature. It is a double fail-safe system. It should keep the temperatures low and isolate the RZC.
Using the aforementioned configuration, the top half of the chamber will have the breathable PP fabric. The whole top of the system, spanning the 10'x10' grow tent footprint, will be rigid insulation. This will isolate the RZC from the grow area.
The primary cooling fans will be thermostatically controlled to circulate cool basement air ( ~58F/14C) around the RZC's and indirectly cool them through evaporation of the water on the PP fabric.
They will turn on at 69F/20.5C and off at 65F/18C. The negative pressure will draw the air out of the tent while pulling in cool air from multiple vent ports. This system should cause minimal desiccation.
The secondary fail-safe system consists of fans mounted on the RZC itself and they draw air from the inside of the RZC to the primary cooling system. These have a separate thermostat and alarm. This system activates if the temperature reaches 72F/22C, alarms at 75F/24C. This is a double safety wherein the fans activate and a bypass solenoid triggers the release of mist onto the roots. This mist would spray for 3s/3m controlled by it's own timer. It will cycle until the temperature abnormality is rectified and shut off again. This should prevent desiccation and provide a rapid cooling effect from the H2O delta-Hvap. If the temperature elevates to 75F, an audible alarm is sounded.
All of this is in addition to the accumulator, which should be at the ambient 58F, as it is housed externally. The mist dispensations should absorb heat leakage in the amount of 4J/mL/C of H2O. This will be the primary temperature buffer for the system along with the normal evaporation through the PP fabric.
I've based the temperature set points on the literature and experience, but they are subject to modification. From my recent testing of a smaller mock system, this system design should have traction. Advice, concerns, criticisms, comments are always welcome.
- ZXC

I guess it's time for a progress update. So, the plants have been looking a little yellow and the ppm's have been dropping daily. Even with add backs, the nutrients are being consumed quickly. I needed to increase the concentration and change the ratios to accommodate the nitrogen and magnesium consumption. I played around with the composition until I finally got a 3-1-2, with increased Mg. Here is a pic of the formula.

They have also become crowded in one of the LPA totes, so I needed to construct another.

It's a simplistic design, but it should house them until the clones are ready for the main system.

So, once that was in place, I consolidated all of the plants. Even the crispy walking dead plant that is in a slow recovery. These were moved to the 4x4 tent. They are now getting about 500 uMol PAR, which is pretty even throughout the tent. I'm using mixed lighting, a 2400W (500W actual) full spec LED and a 500W white COB LED. They are on a 24hr light schedule and getting a DLI of about 35 because I open the tent to the sunlight during the day and it is less intense. Here are some pics of the plants. I have to start erecting the 10x10 tent tomorrow. Lot's of work setting this up.